This invention relates broadly to concrete cutting apparatus and, more particularly, pertains to a multi-directional, carriage-mounted saw for cutting extruded, prestressed concrete slabs.
Concrete slabs are formed on casting beds by extruding machines of the type wherein a frame is mounted on a pair of rails between which a pallet extends. A hopper is mounted on the frame and feeds concrete or the like downwardly to a set of augers which are rotated by a source of power. These augers pick up the concrete and compress it within a packing chamber to form a slab with long bores therethrough formed by the augers. The compression of the concrete drives the machine forwardly on the rails with the slab being extruded therebehind.
Conventional extruding machines are of sufficient dimensions to form slabs in long lengths of 400-600 feet, with widths of 4-8 feet and thicknesses of 4-20 inches. Because of their immense mass, these slabs must be cut to a more reasonable size before they can be used in the construction of buildings. Traditionally, construction workers will use various sawing apparatus to make a longitudinal cut or a 90.degree. cross-cut in order to obtain a workable piece of material. After the sawed piece is lifted from the casting bed, such as by a crane or the like, and transported to a remote building site, a road saw or chain saw is typically used to perform additional cutting or trimming often along an angular orientation to meet the specifications of the building architect.
Efforts to produce concrete slabs in the manner described above create problems in wasted concrete and additional handling of severed concrete slabs. Saws used at the building site must be blocked and braced to make additional cuts, and additional lifting equipment and manpower must be made available, both of which contribute to undesirably high labor and production costs. As more architects design buildings exhibiting predominantly angular features, it is desirable to offer a concrete saw which is able to improve upon the initial cutting operation and reduce the amount of expenditures currently incurred in the formation of concrete building material.
The prior art provides other types of saws that could be used for cutting extruded concrete slabs but they present some distinct disadvantages. For instance, U.S. Pat. No. 4,576,076 issued Mar. 18, 1976 to Pyle discloses a saw which is able to make longitudinal cross-cut and angular cuts using a blade which can be moved in various motions relative to the workpiece on a horizontal table. Such table saws are generally not suitable for cutting concrete slabs because they have a much different mounting and carriage that requires the workpiece to be moved by hand along the table while the saw is manipulated using a series of manual adjustments.
The prior art does provide at least one self-propelled, rail-mounted saw for cutting hollow, prestressed slabs along straight and angular paths. An example of such saw is the EL-1100 Hollow Core Slab Saw. This saw relies upon sophisticated electronic control to move a cutting blade and supporting framework along travel and cutting axes simultaneously. Unfortunately, this slab saw is unduly complicated and extremely expensive for the majority of customers.
Accordingly, there remains a need for an affordable, reliable and simplified concrete slab saw which travels along and selectively cuts an extruded slab longitudinally, laterally and angularly at a casting site on the same casting bed on which the extruder has traveled.